One of the standard definitions of art holds art is anything the viewer or listener finds aesthetically pleasing.  That broad definition may hold as a quick answer, but does not answer the question entirely since what one person may see as art may not be appreciated by another.  For example, most people would agree a painting of The Madonna and Child is art, yet some years ago such an image made of cow feces was exhibited and generally panned.  Is then the medium the message?  Who  gets to make the rules and definitions?  What actually constitutes a work of art?